Moving on to the latest developments in Japan's ongoing nuclear crisis highly radioactive substances were detected in parts of Tokyo.
Japan's Asahi Shimbun reports about 3,200 and nearly 2-thousand becquerels of radioactive cesium per kilogram were found in the soil of Tokyo districts of Koto and Chiyoda, respectively, from testing conducted between April 10th and the 20th.
This amount is higher than what was found in the prefectures near the Fukushima plant and experts warn that other areas may be subject to radiation contamination as clusters of clouds containing radioactive material remain in the atmosphere.
Meanwhile, the plant's main operator, TEPCO, says that over 3-thousand tons of contaminated water has been found in the basement of the No. 1 reactor, causing a delay in Japan's latest approach to cool down the reactors.

MAY 15, 2011
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Radiation Detected in Tea Leaves in Japan

By JURO OSAWA
MAY 11, 2011, 1:28 P.M. ET

TOKYO—A prefecture just south of Tokyo said it had detected higher-than-permissible amounts of radioactive material in tea leaves, in a reminder that Japan's radioactive-contamination problems are far from over.

The contamination—the first case in nearly a month that an agricultural product has been found tainted outside Fukushima Daiichi's home prefecture—is also the first time that any agricultural item from Kanagawa Prefecture, which includes Yokohama, was found to contain an excessive level of radioactivity.

Japan is still struggling to cope with its worst-ever nuclear disaster at the stricken power plant in Fukushima Prefecture, but concerns over radioactivity in food and drinking water had been easing over the past few weeks, at least outside the most-contaminated areas near the plant. In some prefectures, previously banned shipments of certain vegetables have since resumed, as repeated tests showed declines in contamination levels.

Before the latest case of Kanagawa tea leaves, the last time any prefecture outside Fukushima reported higher-than-permissible contamination in any agricultural product was spinach from Ibaraki Prefecture on April 12, according to Japan's health ministry.

According to Kanagawa officials, a sample of tea leaves collected May 9 from the city of Minamiashigara, in the western part of the prefecture, was found to contain 550 becquerels of cesium per kilogram in the first test; the second test of the same sample detected 570 becquerels. The difference between the two readings is within the margin of error in such tests, the officials said.

Since the discovery, the prefecture has suspended shipments of tea leaves from all of Kanagawa, not just Minamiashigara.

Kanagawa tested tea leaves for the first time because local farmers were about to start shipping this year's tea leaves they had just picked. The prefecture had been testing other agricultural products, but hadn't found any problems of excessive contamination.

"Before the tea leaves, Kanagawa's other agricultural products had shown no apparent increase in the amount of radioactive materials," which had always been well below the Japanese government's regulatory limits, said Hideto Funahashi, a Kanagawa government official in charge of the prefecture's agricultural issues.

The total area contaminated with radiation from the Fukushima No. 1 nuclear power plant is estimated at about 800 square kilometers, or about 40 percent the size of Tokyo, according to a radiation map created by the science ministry and U.S. Department of Energy.

The report uses the same level of contamination (555,000 becquerels or higher of cesium-137) that was used to issue compulsory evacuation orders in the Chernobyl nuclear accident in 1986. ...

The report's radiation levels were determined in April by measuring, from about 150-700 meters above ground, levels of accumulated radiation on the ground. The areas measured were divided into 1- to 2-square-kilometer zones.

According to the map, about 800 square kilometers are contaminated with accumulated cesium-137 of 600,000 becquerels or higher per square meter. The substance has a half-life of about 30 years.